JP2004086932A - Draw type optical recording medium and its recoding and reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DRAW type optical recording medium in which simple layer constitution is provided, production cost is reduced, no large limitation is imposed on a recording and reproducing wavelengths, wavelength dependence on recording characteristics is made less, stringent optical conditions normally imposed on an organic material are not required even though organic material is used, good jitter resistance and wide recording power margin are realized even though a recording principle mainly employing deformation is used, surface recording or recording by a high NA lens is facilitated and high density recording is accomplished and to provide its recording and reproducing method. <P>SOLUTION: The medium has a structure in which a deformation layer, that is deformed by recording, is held by a deformation shape compensating layer, that compensates for the deformation shape of the deformation layer, and a deformation receiving layer that receives deformation of the deformation layer. In the medium, the boundary between the deformation layer and the deformation receiving layer is used as main reflection boundary and reproducing is conducted from the deformation receiving layer side. <P>COPYRIGHT: (C)2004,JPO

Description

【００３９】
実施例１
溝深さ５５ｎｍの案内溝を有するポリカーボネート基板上に、変形形状補償層としてＤＶＤ−Ｒに利用できる上記〔化１〕の色素からなる色素層を厚さ約６０ｎｍ、その上に光吸収機能を有する変形層としてＳｉＣを厚さ１０ｎｍ、更にその上に変形受容層としてポリスチレン樹脂を厚さ約２μｍ設けた光記録媒体を作製した。
この光記録媒体に対して、パルステック工業製の光ディスク評価装置、ＤＤＵ−１０００（波長：４０５ｎｍ、ＮＡ：０．６５）を用いて、ポリスチレン樹脂層側から９．７ｍＷのレーザ光を照射し、ランド部（入射レーザ光側から見て、手前側にある溝位置）に、記録周波数６５．４ＭＨｚ、記録線速度６．０ｍ／ｓで８−１６変調の信号を記録した。
その結果、変調度が約６１％で、記録極性がＨｉｇｈ　ｔｏ　Ｌｏｗであり、比較例１と同様に明瞭なアイパターンが得られ、ジッタ（σ／Ｔｗ）は８．０％となった。
また、記録パワーに対するジッタ特性は、図２４の■で示した線のようになり、比較例１のディスクに比べて（図２４の◆で示した線）、記録パワーマージンが広いことが確認できた（変形受容層の効果が確認できた）。
この時、ポリスチレン樹脂層を剥がし、変形層の変形状態をＡＦＭによって確認したところ、図２３に示すように、変形層は入射光側（ポリスチレン樹脂層側）に変形しており、またその変形形状の対称性は良好であった。なお、図２３中の白い点線はマーク中心を示す線である。
【００４０】
比較例２
溝深さ５５ｎｍの案内溝を有するポリカーボネート基板上に、光吸収機能を有する変形層としてＳｉＣを厚さ１０ｎｍ設けた光記録媒体を作製した。
この光記録媒体に対して、パルステック工業製の光ディスク評価装置、ＤＤＵ−１０００（波長：４０５ｎｍ、ＮＡ：０．６５）を用いて、ＳｉＣ側から８．０ｍＷのレーザ光を照射し、ランド部（入射レーザ光側から見て、手前側にある溝位置）に、記録周波数６５．４ＭＨｚ、記録線速度６．０ｍ／ｓで８−１６変調の信号を記録した。
その結果、変調度が約７０％で、記録極性がＨｉｇｈ　ｔｏ　Ｌｏｗであり、図１８に示すような、比較的良好なアイパターンが得られたが、ジッタ（σ／Ｔｗ）は１０．４％と大きくなった。
また、記録パワーに対するジッタ特性は、図２０の●で示した線のようになり、前述した比較例１に比べて、ジッタの値が悪く、また記録パワーマージンも狭いことが確認できた。
この時、変形層の変形状態をＡＦＭによって確認したところ、図２１に示すように、変形層は入射光側に変形しているが、その変形形状の対称性が大きく崩れていた。なお、図２１中の白い点線はマーク中心を示す線である。
以上、比較例１と比較例２の結果から、変形形状補償層の有効性が示され、比較例１と実施例１の結果から、変形受容層の有効性が示された。
【００４１】
実施例２
溝深さ５５ｎｍの案内溝を有するポリカーボネート基板上に、変形形状補償層として青色レーザ波長に吸収を持つ下記〔化２〕からなる色素層を厚さ約２０ｎｍ、光吸収機能を有する変形層としてＳｉＣを厚さ約５ｎｍ、変形受容層としてポリスチレン樹脂からなる層を厚さ約８０ｎｍ、反射層としてＡｇを厚さ約１００ｎｍ設けた光記録媒体を作製した。
この光記録媒体に対して、パルステック工業製の光ディスク評価装置、ＤＤＵ−１０００（波長：４０５ｎｍ、ＮＡ：０．６５）を用いて、基板側から９．５ｍＷのレーザ光を照射し、ランド部（入射レーザ光側から見て、奥側にある溝位置）に、記録周波数６５．４ＭＨｚ、記録線速度６．０ｍ／ｓで８−１６変調の信号を記録した。
その結果、記録パワーに対するジッタ特性は、図２５の■で示した線のようになり、後述する比較例３に比べて、ジッタの値が良いことが確認できた。
また、繰り返し再生による再生劣化が殆どなく、記録部の色素層は分解・変質を起していることが確認できた。
【００４２】
【化２】

【００４３】
比較例３
溝深さ５５ｎｍの案内溝を有するポリカーボネート基板上に、光吸収機能を有する変形層としてＳｉＣを厚さ約１０ｎｍ、変形受容層としてポリスチレン樹脂からなる層を厚さ約８０ｎｍ、反射層としてＡｇを厚さ約１００ｎｍ設けた光記録媒体を作製した。
この光記録媒体に対して、パルステック工業製の光ディスク評価装置、ＤＤＵ−１０００（波長：４０５ｎｍ、ＮＡ：０．６５）を用いて、基板側から９．８ｍＷのレーザ光を照射して、ランド部（入射レーザ光側から見て、奥側にある溝位置）に、記録周波数６５．４ＭＨｚ、記録線速度６．０ｍ／ｓで８−１６変調の信号を記録した。
その結果、記録パワーに対するジッタ特性は、図２５の◆で示した線のようになり、前述の実施例２に比べて、ジッタの値が悪かった。
【００４４】
以上、実施例において、本発明の変形形状補償層と変形受容層の効果を確認したが、本発明では、光吸収層に記録に必要な光吸収機能を持たせることにより、色素層（例えば変形形状補償層）に大きな光吸収機能を持たせる必要がなくなるため、色素層の膜厚を薄膜化でき、従って、浅溝基板の利用が可能であることを確認した。
また、上記実施例では、何れも記録をランド部に行ったが、これは、変形層の変形形状を観察し易くするためであって、本発明はランド記録に限定されるものではない。
【００４５】
次に、参考例１〜８により、変形層とその隣接層の界面が主反射界面となる場合において、変形層を入射光側に変形させることの重要性を示すが、これらの参考例では、変形層の変形の作用を明確にするため、変形形状補償層を設けない光記録媒体で実験を行った（変形形状補償層を設けた場合も、これらの参考例と同様な現象となる）。
なお、図１０〜図１７は、それぞれ参考例１〜８の記録結果を示す図である。図１０（ａ）〜図１７（ａ）は、参考例１〜８の再生信号（ＲＦレベル）の記録マーク長（Ｍａｒｋ　Ｌｅｎｇｔｈ）依存性を測定した結果を示す図であり、各図中の、Ｕｎｒｅｃは未記録時の再生信号（ＲＦレベル）を、Ｔｏｐはマーク列を記録した時の最大再生信号レベル（即ちスペース部）を、Ｂｏｔｔｏｍはマーク列を記録した時の最小再生信号レベルを、ＭＡは（Ｔｏｐ−Ｂｏｔｔｏｍ）／Ｔｏｐで計算される変調度を示す。
また、図１０（ｂ）〜図１６（ｂ）には、３Ｔマークを連続して記録した場合の再生信号、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを、図１０（ｃ）〜図１６（ｃ）には、６Ｔマークを連続して記録した場合の再生信号、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを、図１０（ｄ）〜図１７（ｄ）には、３Ｔマークを連続して記録した場合の再生信号、１４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示した。
【００４６】
参考例１
溝深さ５５ｎｍの案内溝を有するポリカーボネート基板上に、光吸収機能を有する変形層としてＳｉＣを厚さ１０ｎｍ設けた光記録媒体を作製した。
この光記録媒体に対して、パルステック工業製の光ディスク評価装置、ＤＤＵ−１０００（波長：４０５ｎｍ、ＮＡ：０．６５）を用いて、基板側から５．０ｍＷのレーザ光を照射し、グルーブ部（入射レーザ光側から見て、手前側にある溝位置）に、記録周波数６５．４ＭＨｚ、記録線速度６．０ｍ／ｓで３Ｔ〜１４Ｔマークをそれぞれ単独で記録した。
なお、ＳｉＣは入射光とは反対側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１０（ａ）の結果から、記録マーク長によらずＨｉｇｈ　ｔｏ　Ｌｏｗ記録が行えている可能性があることが確認できる。
更に、図１０（ｂ）〜図１０（ｄ）の結果から、３Ｔ、４Ｔ、６Ｔ、８Ｔ、１４Ｔとも、マーク長記録が可能な再生信号波形を示すことが分る。
【００４７】
参考例２
記録パワーを６．０ｍＷとした点以外は参考例１と全く同様の実験を行った。なお、ＳｉＣは入射光とは反対側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１１（ａ）の結果から、記録マーク長によって記録極性が変化すること、即ち、短マークではＨｉｇｈ　ｔｏ　Ｌｏｗ記録であるが、長マークではＨｉｇｈ　ｔｏ　Ｌｏｗ記録とＬｏｗ　ｔｏ　Ｈｉｇｈ記録が混在したような信号が発生し、マーク長記録が困難となることが分る。
更に、図１１（ｂ）〜図１１（ｄ）の結果から、３Ｔ、４Ｔはマーク長記録が可能な再生信号波形を示すが、６Ｔ、８Ｔ、１４Ｔはマーク中央部のＲＦレベルが大きく上昇した再生信号波形を示し〔６Ｔ、８Ｔでは、再生信号の周期が本来の再生信号の倍に見える。このことは図１０（ｃ）と比べるとよく分る〕、マーク長記録が困難となることが分る。
【００４８】
参考例３
基板側から６．０ｍＷのレーザ光を照射してランド部（入射レーザ光側から見て奥側にある溝位置）に記録した点以外は参考例１と全く同様の実験を行った。なお、ＳｉＣは入射光とは反対側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１２（ａ）の結果から、記録マーク長によって記録極性が変化する傾向、即ち、短マークではＨｉｇｈ　ｔｏ　Ｌｏｗ記録であるが、長マークではＨｉｇｈ　ｔｏ　Ｌｏｗ記録とＬｏｗ　ｔｏ　Ｈｉｇｈ記録が混在したような信号が発生する傾向が見られ、マーク長記録が困難となる可能性があることが分る。更に、図１２（ｂ）〜図１２（ｄ）の結果から、３Ｔ、４Ｔ、６Ｔ、８Ｔは、マーク長記録が可能な再生信号波形を示すが、１４Ｔはマーク中央部のＲＦレベルが大きく上昇した再生信号波形を示し、マーク長記録が困難となることが分る。
【００４９】
参考例４
基板側から７．０ｍＷのレーザ光を照射してランド部（入射レーザ光側から見て奥側にある溝位置）に記録した点以外は参考例１と全く同様の実験を行った。なお、ＳｉＣは入射光とは反対側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１３（ａ）の結果から、記録マーク長によって記録極性が変化すること、即ち、短マークではＨｉｇｈ　ｔｏ　Ｌｏｗ記録であるが、長マークではＨｉｇｈ　ｔｏ　Ｌｏｗ記録とＬｏｗ　ｔｏ　Ｈｉｇｈ記録が混在したような信号が発生し、マーク長記録が困難となることが分る。
更に、図１３（ｂ）〜図１３（ｄ）の結果から、３Ｔ、４Ｔは、マーク長記録が可能な再生信号波形を示すが、６Ｔ、８Ｔ、１４Ｔはマーク中央部のＲＦレベルが大きく上昇した再生信号波形を示し〔例えば６Ｔでは再生信号の周期が本来の再生信号の倍に見える。このことは図１０（ｃ）と比べるとよく分る〕、マーク長記録が困難となることが分る。
【００５０】
以上、参考例１〜４の結果から、変形層とその隣接層の界面が主反射界面となり、基板上に光吸収機能を有する変形層を設けたような単純層構成で、変形層を入射光と反対側に変形させる場合は（今の場合、基板側から記録再生する方式では）、マーク長による記録再生が困難である場合が多く、また記録極性がＬｏｗ
ｔｏ　Ｈｉｇｈ化する場合が多いことが確かめられた。
【００５１】
参考例５
溝深さ５５ｎｍの案内溝を有するポリカーボネート基板上に、光吸収機能を有する変形層としてＳｉＣを厚さ１０ｎｍ設けた光記録媒体を作製した。
この光記録媒体に対して、パルステック工業製の光ディスク評価装置、ＤＤＵ−１０００（波長：４０５ｎｍ、ＮＡ：０．６５）を用いて、ＳｉＣ側から８．０ｍＷのレーザ光を照射し、ランド部（入射レーザ光側から見て、手前側にある溝位置）に、記録周波数６５．４ＭＨｚ、記録線速度６．０ｍ／ｓで３Ｔ〜１４Ｔマークをそれぞれ単独で記録した。
なお、ＳｉＣは入射光側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１４（ａ）の結果から、記録マーク長によらずＨｉｇｈ　ｔｏ　Ｌｏｗ記録が行えている可能性があることが確認できる。
更に、図１４（ｂ）〜図１４（ｄ）の結果から、３Ｔ、４Ｔ、６Ｔ、８Ｔ、１４Ｔとも、マーク長記録が可能な再生信号波形を示すことが分る。
【００５２】
参考例６
記録パワーを９．０ｍＷとした点以外は参考例５と全く同様の実験を行った。なお、ＳｉＣは入射光側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１５（ａ）の結果から、記録マーク長によらずＨｉｇｈ　ｔｏ　Ｌｏｗ記録が行えている可能性があることが確認できる。
更に、図１５（ｂ）〜図１５（ｄ）の結果から、３Ｔ、４Ｔ、６Ｔ、８Ｔ、１４Ｔとも、マーク長記録が可能な再生信号波形を示すことが分る。
【００５３】
参考例７
ＳｉＣ側から７．０ｍＷのレーザ光を照射してグル−ブ部（入射レーザ光側から見て奥側にある溝位置）に記録した点以外は、参考例５と全く同様の実験を行った。なお、ＳｉＣは入射光側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１６（ａ）の結果から、記録マーク長によらずＨｉｇｈ　ｔｏ　Ｌｏｗ記録が行えている可能性があることが確認できる。
更に、図１６（ｂ）〜図１６（ｄ）の結果から、３Ｔ、４Ｔ、６Ｔ、８Ｔ、１４Ｔとも、マーク長記録が可能な再生信号波形を示すことが分る。
【００５４】
参考例８
基板側から８．０ｍＷのレーザ光を照射してグル−ブ部（入射レーザ光側から見て奥側にある溝位置）に記録した点以外は参考例５と全く同様の実験を行った。なお、ＳｉＣは入射光側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１７（ａ）の結果から、記録マーク長によらずＨｉｇｈ　ｔｏ　Ｌｏｗ記録が行えている可能性があることが確認できる。
更に、図１７（ｄ）の結果から、最短及び最長マークとも、マーク長記録が可能な再生信号波形を示すことが分る。
【００５５】
以上、参考例５〜８に示したように、変形層とその隣接層の界面が主反射界面となり、基板上に光吸収機能を有する変形層を設けただけの単純な光記録媒体であって、変形層を入射光側に変形させる場合は（今の場合、反基板側から記録再生する方式では）、マーク長記録が可能で、Ｈｉｇｈ　ｔｏ　Ｌｏｗ記録が行える可能性があることが実験によって証明された。
【００５６】
【発明の効果】
本発明１〜２２によれば、単純層構成で安価に製造可能であり、記録再生波長に大きな制限がなく、記録特性の波長依存性が少なく、有機材料を用いる場合でも有機材料に対して従来のような厳しい光学的条件が不要であり、変形を主体とする記録原理を用いているにも関わらず良好なジッタと広い記録パワーマージンを実現でき、表面記録或いは高ＮＡレンズによる記録に対応でき高密度化が達成できるという特性を有する追記型光記録媒体及びその記録再生方法を提供できる。
【図面の簡単な説明】
【図１】変形層の変形形状の対称性を説明する図。
（ａ）　対称性が悪化した変形形状の例。
（ｂ）　理想的な変形形状の例。
【図２】マーク長記録の記録マークを再生した場合の再生信号の波形を説明する図。
（ａ）　一般的な場合
（ｂ）　記録マークの前後エッジ近傍で変極点を持つ微分波形
（ｃ）　記録マークの中心近傍で変極点を持つ微分波形
【図３】変形層に変形形状補償層と変形受容層を隣接させた構造を有する例を示す図。
【図４】図３の構造を有し、主反射界面が変形層と変形受容層の界面にある場合の、変形層の変形方向と再生方向を示した図。
【図５】図４の構造と機能を有する層構成を、実際の追記型光記録媒体に適用した例、即ち、基板上に図４の層構成を積層した例を示す図。
【図６】図４の構造と機能を有する層構成を、実際の追記型光記録媒体に適用した別の例、即ち、基板上に図４の層構成を積層し、更に変形受容層上にカバー層を設けた例を示す図。
【図７】図４の構造と機能を有する層構成を、実際の追記型光記録媒体に適用した更に別の例、即ち、基板上に図４の層構成を積層し、更に変形受容層上に接着層を介してカバー層を設けた例を示す図。
【図８】図３の構造を有し、変形受容層の変形層とは反対側の隣接層として反射層を有する構造であって、主反射界面が変形受容層と反射層の界面にある場合の、変形層の変形方向と再生方向を示した図。
【図９】図８の構造と機能を有する層構成を、実際の追記型光記録媒体に適用した例、即ち、基板上に図８の層構成を積層した例を示す図。
【図１０】参考例１の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１１】参考例２の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１２】参考例３の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１３】参考例４の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１４】参考例５の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び
未記録時の再生信号レベルを示す。
【図１５】参考例６の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１６】参考例７の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ）　３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ）　６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１７】参考例８の記録結果を示す図。
（ａ）　記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｄ）　３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１８】比較例２の光記録媒体のアイパターンを示す図。
【図１９】比較例１の光記録媒体のアイパターンを示す図。
【図２０】比較例１及び比較例２の各光記録媒体の記録パワーに対するジッタ特性を示す図。
【図２１】比較例２の光記録媒体の変形層の変形状態をＡＦＭによって測定した図。
【図２２】比較例１の光記録媒体の変形層の変形状態をＡＦＭによって測定した結果を示す図。
【図２３】実施例１の光記録媒体のポリスチレン層を剥がし、変形層の変形状態をＡＦＭによって測定した結果を示す図。
【図２４】比較例１及び実施例１の各光記録媒体の記録パワーに対するジッタ特性を示す図。
【図２５】実施例２及び比較例３の各光記録媒体の記録パワーに対するジッタ特性を示す図。
【図２６】従来のディスクの層構成を示す図。
【符号の説明】Ａ　変形層と変形形状補償層が剥離した部分、変形形状補償層が膨張した部分、或いは変形層が膨張した部分
Ｍａｒｋ　Ｌｅｎｇｔｈ　マーク長
Ｔ　基準クロック
ＲＦ　Ｌｅｂｅｌ（Ｖ）　ＲＦ（再生信号）レベル（ボルト）
Ｍｏｄｕｌａｔｅｄ　ａｍｐｌｉｔｕｄｅ　変調度
Ｕｎｒｅｃ　未記録時の再生信号（ＲＦ）レベル
Ｔｏｐ　マーク列を記録した時の最大再生信号レベル（即ちスペース部）
Ｂｏｔｔｏｍ　マーク列を記録した時の最小再生信号レベル（即ちマーク部）
ＭＡ　（Ｔｏｐ−Ｂｏｔｔｏｍ）／Ｔｏｐで計算される変調度
Ｔｉｍｅ０．５（μｓ／ｄｉｖ）　時間（１メモリ０．５マイクロ秒）
σ／Ｔｗ　ジッタ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a write-once read-many (WORM) optical recording medium, and more particularly to a write-once optical recording medium capable of high-density recording even with a blue laser wavelength of about 350 to 500 nm.
[0002]
[Prior art]
◎ About write-once optical recording media compatible with blue laser
The development of a blue laser capable of recording at a very high density is progressing rapidly, and a write-once optical recording medium corresponding to the development is being developed.
In conventional write-once optical recording media, recording pits are formed by irradiating a laser beam to a recording layer made of an organic material and causing a change in refractive index mainly due to decomposition and alteration of the organic material. The optical constant and decomposition behavior of the organic material used are important factors for forming a good recording pit.
Therefore, it is necessary to select an appropriate material having an optical property and a decomposition behavior with respect to a blue laser wavelength as the organic material used for the recording layer. In other words, the recording / reproducing wavelength is set to a large absorption band in order to increase the reflectance at the time of non-recording and to cause the organic material to be decomposed by laser irradiation to cause a large change in the refractive index (this provides a large degree of modulation). It is selected so as to be located on the long wavelength side skirt.
[0003]
This is because the bottom of the large absorption band of the organic material on the long wavelength side is a wavelength region having an appropriate absorption coefficient and obtaining a large refractive index.
However, an organic material having optical properties with respect to the wavelength of a blue laser having a value comparable to that of a conventional blue laser has not yet been found. This means that in order to obtain an organic material having an absorption band near the blue laser wavelength, it is necessary to reduce the molecular skeleton or shorten the conjugated system, but this causes a decrease in the absorption coefficient, that is, a decrease in the refractive index. That's why.
That is, there are many organic materials having an absorption band near the blue laser wavelength, and the absorption coefficient can be controlled. However, since the organic material does not have a large refractive index, a large degree of modulation cannot be obtained.
[0004]
Examples of the organic material corresponding to a blue laser include those described in JP-A-2001-181524, JP-A-2001-158865, JP-A-2000-343824, JP-A-2000-343825, and JP-A-2000-335110. is there.
However, in these publications, the examples only measure the spectra of the solution and the thin film, but do not describe recording and reproduction.
In each of JP-A-11-221964, JP-A-11-334206 and JP-A-2000-43423, recording is described in Examples, but the recording wavelength is 488 nm, and the recording condition and recording density are not described. However, there is only a statement that good recording pits were formed.
In JP-A-11-58955, although recording is described in Examples, the recording wavelength is 430 nm, and there is no description about recording conditions or recording density, and there is a description that a good degree of modulation was obtained. Only.
[0005]
JP-A-2001-39034, JP-A-2000-149320, JP-A-2000-113504, JP-A-2000-108513, JP-A-2000-222772, JP-A-2000-218940, JP-A-2000-222277, In JP-A-2000-158818, JP-A-2000-280621, and JP-A-2000-280620, there are examples of recording at a recording wavelength of 430 nm and NA of 0.65 in the examples, but low recording with the shortest pit of 0.4 μm. Density condition (recording density equivalent to DVD).
In Japanese Patent Application Laid-Open No. 2001-146074, the recording / reproducing wavelength is 405 to 408 nm, but there is no specific description about the recording density, and the recording condition is the low recording density of 14T-EFM signal recording.
[0006]
Further, regarding the layer configuration and recording method different from those of the conventional CD and DVD optical recording media, the following techniques are disclosed.
Japanese Patent Application Laid-Open No. 7-304258 discloses a technique of performing recording by changing the extinction coefficient (absorption coefficient in the present invention) of a saturable absorbing dye in a layer structure of a substrate / saturable absorbing dye-containing layer / reflective layer. It has been disclosed.
Japanese Patent Application Laid-Open No. 8-83439 discloses that a recording is performed by discoloring or deforming the metal vapor deposited layer by heat generated by the light absorbing layer in a layer structure of substrate / metal vapor deposited layer / light absorbing layer / protective sheet. Performing techniques are disclosed.
Japanese Patent Application Laid-Open No. 8-138245 discloses that recording is performed by changing the depth of a groove portion by changing the film thickness of a recording layer in a layer structure of a substrate / dielectric layer / recording layer including a light absorber / reflection layer. The technology is disclosed.
Japanese Patent Application Laid-Open No. 8-2977838 discloses a technique of performing recording by changing the thickness of a recording layer by 10 to 30% in a layer structure of a substrate / a recording layer including a light absorber / a metal reflection layer. I have.
[0007]
Japanese Unexamined Patent Publication No. Hei 9-198714 discloses a layer structure of a substrate / a recording layer containing an organic dye / a metal reflective layer / a protective layer, in which the groove width of the substrate is increased by 20 to 40% with respect to an unrecorded portion. A technique for performing recording is disclosed.
Japanese Patent No. 2506374 discloses a technique in which recording is performed by forming a bubble by deforming a metal thin film in a layer structure of a substrate / intermediate layer / metal thin film.
Japanese Patent No. 2591939 has a layer structure of substrate / light absorbing layer / recording auxiliary layer / light reflecting layer, in which the recording auxiliary layer is deformed into a concave shape and the light reflecting layer is formed into a concave shape along with the deformation of the recording auxiliary layer. There is disclosed a technique of performing recording by deforming.
Japanese Patent No. 2591940 discloses a recording assisting device having a layer structure of substrate / light absorbing layer / porous recording auxiliary layer / light reflecting layer or substrate / porous recording auxiliary layer / light absorbing layer / light reflecting layer. There is disclosed a technique in which recording is performed by deforming a layer in a concave shape and deforming a light reflecting layer in a concave shape along with the deformation of the recording auxiliary layer.
Japanese Patent No. 2591941 discloses that a light absorbing layer is deformed in a concave shape along with a light absorbing layer and a light reflecting layer is deformed in a concave shape in accordance with the deformation of the light absorbing layer. There is disclosed a technique of performing recording by causing the recording to be performed.
[0008]
Japanese Patent No. 2982925 discloses that a recording / assisting layer and an organic dye are compatible with each other in a layer structure of a substrate / a recording layer containing an organic dye / a recording auxiliary layer, and the absorption spectrum of the organic dye is shifted to a shorter wavelength side. Discloses a technique for performing recording.
Japanese Patent Application Laid-Open No. 9-265660 discloses a multilayer structure in which a reflective layer, a composite layer having the function of a recording layer, and a protective layer are sequentially formed on a substrate. Recording is performed by forming a bump between the substrate and the composite functional layer. Performing techniques are disclosed. Note that the composite functional layer is defined as a metal such as nickel, chromium, or titanium, or an alloy thereof.
Japanese Patent Application Laid-Open No. Hei 10-134415 discloses a layer structure in which a metal thin film layer, a deformable buffer layer, a reflective layer, and a protective layer are sequentially formed on a substrate, and the substrate and the metal thin film layer are deformed at the same time. A technique for performing recording by reducing the thickness of the buffer layer is disclosed. The metal thin film layer is defined as a metal such as nickel, chromium, and titanium, or an alloy thereof. Further, it is described that a resin which is easily deformable and has an appropriate fluidity is used for the buffer layer, and a dye may be contained in the buffer layer to promote the deformation.
[0009]
Japanese Patent Application Laid-Open No. H11-306591 discloses a layer configuration in which a metal thin film layer, a buffer layer, and a reflective layer are sequentially laminated on a substrate, in which the substrate and the metal thin film layer are deformed. A technique for performing recording by changing an optical constant is disclosed. Note that the metal thin film layer is preferably made of a metal such as nickel, chromium, or titanium, or an alloy thereof. The buffer layer is made of a mixture of a dye and an organic polymer, and a dye having a large absorption band near the recording / reproducing wavelength is used.
Japanese Patent Application Laid-Open No. H10-124926 discloses a layer structure in which a metal recording layer, a buffer layer, and a reflective layer are sequentially laminated on a substrate, in which the substrate and the metal recording layer are deformed. A technique for performing recording by changing an optical constant is disclosed. It is described that a metal such as nickel, chromium, and titanium, or an alloy thereof is preferable for the metal recording layer. The buffer layer is made of a mixture of a dye and a resin, and a dye having a large absorption band near the recording / reproducing wavelength is used.
[0010]
As described above, the above various prior arts do not aim at realizing an optical recording medium in the blue laser wavelength region, and are not effective layer configurations or recording methods in the blue laser wavelength region.
In particular, in the vicinity of 405 nm, which is the center of the oscillation wavelength of a blue semiconductor laser currently in practical use, almost all organic materials having an optical constant similar to the optical constant required for the recording layer of the conventional write-once optical recording medium are almost used. Almost no. Further, there is no example in which recording conditions are clarified in the vicinity of 405 nm and recording is performed at a higher recording density than that of DVD.
Furthermore, many of the examples in the above-mentioned conventional technology are experiments with a conventional disk configuration (see FIG. 26). Although a configuration different from the conventional disk configuration has been proposed, the dye used therein is The same optical characteristics and functions as in the past are required, and there is no effective proposal for a layer configuration, a recording principle, and a recording method that can easily realize a write-once optical recording medium made of an organic material in a blue laser wavelength region.
[0011]
In addition, in a conventional write-once optical recording medium using an organic material, a large refractive index and a relatively small absorption coefficient (approximately 0.05 to 0.07) with respect to the recording / reproducing wavelength are obtained from the viewpoint of securing the degree of modulation and the reflectance. Only organic materials with a) can be used.
That is, since the organic material does not have a sufficient absorbing ability to the recording light, it is impossible to reduce the thickness of the organic material, and therefore, it is necessary to use a substrate having a deep groove. (Because the organic material is usually formed by a spin coating method, the organic material is buried in a deep groove to increase the thickness). Therefore, it is very difficult to form a substrate having a deep groove, which has been a factor of deteriorating the quality as an optical recording medium.
Further, in a conventional write-once optical recording medium using an organic material, the main absorption band of the organic material exists near the recording / reproducing wavelength, so that the wavelength dependence of the optical constant of the organic material increases (the optical constant depends on the wavelength). The problem is that the recording characteristics such as recording sensitivity, modulation degree, jitter, and error rate, and the reflectivity change significantly with respect to fluctuations in the recording / reproducing wavelength due to individual differences in lasers, changes in environmental temperature, etc. was there.
[0012]
[Problems to be solved by the invention]
An object of the present invention is to provide a write-once optical recording medium satisfying the following characteristics a) to e) and a recording / reproducing method thereof.
a) It can be manufactured inexpensively with a simple layer configuration.
b) There is no great limitation on the recording / reproducing wavelength, and the wavelength dependence of the recording characteristics is small.
c) Even when an organic material is used, strict optical conditions as in the related art are not required for the organic material.
d) Good jitter and a wide recording power margin can be realized despite using a recording principle mainly based on deformation.
e) Surface recording or recording with a high NA lens can be supported, and high density can be achieved.
[0013]
[Means for Solving the Problems]
The above object is achieved by the following inventions 1) to 22) (hereinafter, referred to as present inventions 1 to 22).
1) A write-once type characterized in that a deformation layer that causes deformation by recording has a structure sandwiched between a deformation shape compensation layer that compensates for the deformation shape of the deformation layer and a deformation receiving layer that receives deformation of the deformation layer. Optical recording medium.
2) The write-once optical recording medium according to 1), wherein the interface between the deformation layer and the deformation receiving layer is a main reflection interface, and reproduction is performed from the deformation receiving layer side.
3) The write-once optical recording medium according to 2), wherein the recording portion is formed by deformation of the deformation layer toward the deformation receiving layer.
4) The deformation receiving layer has a structure in which a deformation shape compensating layer for compensating for the deformation shape of the deformation layer, a deformation layer for causing deformation by recording, a deformation receiving layer for receiving deformation of the deformation layer, and a reflecting layer are sequentially provided. The write-once optical recording medium according to 1), wherein the interface between the recording layer and the reflection layer is a main reflection interface, and reproduction is performed from the deformation shape compensation layer side.
5) The write-once optical recording medium according to 4), wherein the recording portion is formed by the deformation of the deformation layer toward the deformation receiving layer.
6) The write-once optical recording medium according to any one of 1) to 5), wherein a deformed portion is formed in the deformable layer by a light absorbing function of the deformable layer.
7) The write-once optical recording medium according to any one of 1) to 5), wherein a deformed portion is formed in the deformable layer by a light absorbing function of the deformable shape compensation layer.
8) The deformed layer and the deformed shape compensating layer have a light absorbing function for recording light, and a deformed portion is formed in the deformed layer by the light absorbing function of both, and the light absorbing function of the deformed shape compensating layer is reduced or eliminated by recording. The write-once optical recording medium according to any one of 1) to 5), wherein:
9) The recordable optical recording medium according to any one of 1) to 8), wherein the deformable shape compensation layer is made of an organic material.
10) The recordable optical recording medium according to 9), wherein the organic material is a dye.
11) The write-once optical recording medium according to any one of 1) to 10), wherein the deformation receiving layer is made of a polymer compound.
12) The write-once optical recording medium according to any one of 1) to 11), wherein the deformable layer contains Si or Ge.
13) The write-once optical recording medium according to 12), wherein recording / reproduction is possible in a laser wavelength range of 350 to 500 nm.
14) A write-once type optical recording medium having a structure in which a deformation layer that is deformed by recording is sandwiched between a deformation shape compensation layer that compensates for the deformation shape of the deformation layer and a deformation receiving layer that receives deformation of the deformation layer. What is claimed is: 1. A recording method for a write-once optical recording medium, comprising: deforming a deformable layer toward a deformation receiving layer by recording.
15) A deformable layer that is deformed by recording has a structure in which a deformable shape compensating layer that compensates for the deformed shape of the deformable layer and a deformation receiving layer that receives deformation of the deformable layer are sandwiched between the deformable layer and the deformable layer. A recording method for a write-once optical recording medium in which reproduction is performed from the deformation receiving layer side, with an interface of the receiving layer being a main reflection interface, wherein the deforming layer is deformed to the deformation receiving layer side by recording. Recording method for optical recording media.
16) having a structure in which a deformation shape compensating layer for compensating for the deformation shape of the deformation layer, a deformation layer for causing deformation by recording, a deformation reception layer for receiving deformation of the deformation layer, and a reflection layer are sequentially provided; A method for recording on a write-once optical recording medium, in which reproduction is performed from the deformation shape compensation layer side, with the interface between the reflection layer and the main reflection interface, wherein the recording deforms the deformation layer to the deformation receiving layer side. Recording method of a write-once optical recording medium.
17) The method according to any one of 14) to 16), wherein the deformation of the deformation layer toward the deformation receiving layer is caused by an expansion force of the deformation layer and / or a pressure accompanying a state change of the deformation shape compensation layer. Recording method for a write-once optical recording medium.
18) The deformation shape compensation layer is made of an organic material, and the deformation of the deformation layer toward the deformation receiving layer is caused by the expansion force of the deformation layer and / or the decomposition, explosion, or sublimation of the organic material constituting the deformation shape compensation layer. The recording method of a write-once optical recording medium according to 17), wherein the recording is performed by an accompanying pressure.
(19) The recording method for a write-once optical recording medium according to (18), wherein the organic material is a dye.
20) The method according to 14) to 16), wherein the deformation of the deformation layer toward the deformation receiving layer is caused by the light absorption function of the deformation layer and / or the light absorption function of the deformation shape compensation layer due to irradiation of recording light. The recording method for a write-once optical recording medium according to any one of the above.
21) The deformation layer is deformed to the deformation receiving layer side by the light absorption function of the deformation layer due to the irradiation of the recording light and the light absorption function of the deformation shape compensation layer. The recording method for a write-once optical recording medium according to any one of 14) to 16), wherein the light absorption function is reduced or eliminated.
22) The write-once optical recording medium according to any one of 14) to 21), wherein the deformable layer is made of a material containing Si or Ge, and performs recording and reproduction with a laser beam having a wavelength of 350 to 500 nm. Recording method.
[0014]
Hereinafter, the present invention will be described in detail.
The present inventor has found that a write-once optical recording medium in which only a deformation layer is provided on a substrate cannot provide sufficient recording / reproducing characteristics. That is, in a write-once optical recording medium having a deformable layer provided on a substrate, for example, when the deformable layer has a light absorbing function, the deformable layer can be deformed by irradiating recording light, and a certain degree of recording / reproducing characteristics can be obtained. Although it can be obtained, it has been found that it is not possible to obtain a jitter characteristic comparable to a CD-R or DVD-R.
The reason is that, as a result of the examination, the symmetry of the deformation shape of the deformation layer with respect to the scanning direction of the recording light around the center of the recording mark (hereinafter, simply referred to as the symmetry of the deformation shape) is deteriorated. [See FIG. 1 (a). FIG. 1B shows an example of an ideal deformed shape.
This deterioration in the symmetry of the deformed shape is likely to occur when the mark length is long or when the physical properties (film thickness, hardness, etc.) relating to the deformation of the deformed layer are not optimal.
[0015]
Therefore, the present inventor has studied a method for solving the above problem, and as a result, provided a deformed shape compensation layer adjacent to the deformed layer in order to correct the deformed shape shown in FIG. The idea was to use the pressure due to the state change of the deformed shape compensation layer, and its effectiveness was confirmed.
That is, in order to improve the jitter characteristics, it has been found that it is important to make the deformed shape of the deformed layer a shape with good symmetry, and in the present invention, the deformed shape compensation layer is adjacent to the deformed layer. Is provided to compensate (correct) the distortion of the deformed shape.
On the other hand, the present inventor has found that it is important to control the amount of deformation in order to widen the recording power margin (margin of jitter fluctuation with respect to recording power change).
In the present invention, in order to reduce the variation in the amount of deformation of the deformable layer with respect to the fluctuation in the recording power, a structure in which the deformation receiving layer is provided in the adjacent layer on the side where the deformable layer is deformed.
By changing the hardness, film thickness, and the like of the deformation receiving layer, the deformation amount and the deformation increase / decrease amount can be controlled, and the recording power margin can be expanded.
[0016]
In the present invention, when the interface between the deformable layer and its adjacent layer is the main reflection interface, it is preferable to deform the deformable layer to the incident light side. This is because, when the deformable layer is deformed to the side opposite to the incident light side, the recording polarity becomes Low to High, the recording polarity changes due to the recording mark length or recording power, or the reproduction signal waveform is differentiated. This is because it is easy to do.
In general, in mark length recording, when a recorded mark is reproduced, a reproduced signal (RF signal) as shown in FIG. 2A is obtained, whereas a reproduced signal (RF signal) as shown in FIG. In the present invention, a signal having an inflection point near the leading and trailing edges of the recording mark and near the center of the recording mark is called a differential waveform (differential waveform).
In addition, the main reflection interface referred to in the present invention refers to a reflection interface that has the largest contribution to the reflected light from the optical recording medium due to the irradiation of the recording / reproducing light, and usually has the largest reflection coefficient.
[0017]
The deformable layer used in the present invention is not limited as long as it is deformed by recording. This deformation is caused by expansion of the deformed layer or pressure from another layer.
In the present invention, in order to improve the recording / reproducing characteristics, it is preferable to use a material having a large difference in the complex refractive index from the adjacent layer as the deformable layer.
For example, Au, Ag, Al, Cr, Ni, Al, Fe, Sn and the like are generally mentioned as metals having a small refractive index (complex refractive index real part). In general, as a material having a large refractive index (complex refractive index real part), a material containing Si or Ge (for example, Si, Ge, Si _x Ge _1-x , Mg ₂ Ge, Mg ₂ Si, SiC, etc.); metals such as Nb, Ta, Be, V, or metal oxides thereof (eg, Ta) ₂ O ₅ , Nb ₂ O ₅ Etc.); AlSb, Al _x Ga _1-x As, CdSe, GaSb, Hg _1-x Cd _x Semiconductors such as Te, Se, Te, ZnTe, ZnS, PbS, InP, and GaP are exemplified.
[0018]
When the adjacent layer of the deformable layer has a relatively low refractive index (for example, about 1.8 or less), the material of the deformable layer is Al. ₂ O ₃ , MgO, BeO, ZrO ₂ , UO ₂ , ThO ₂ Oxides such as simple oxides; SiO ₂ , 2MgO ・ SiO ₂ , MgO / SiO ₂ , CaO ・ SiO ₂ , ZrO ₂ ・ SiO ₂ , 3Al ₂ O ₃ ・ 2SiO ₂ 2MgO.2Al ₂ O ₃ ・ 5SiO ₂ , Li ₂ O ・ Al ₂ O ₃ ・ 4SiO ₂ Silicate-based oxides such as Al; ₂ TiO ₅ , MgAl ₂ O ₄ , Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ , BaTiO ₃ , LiNbO ₃ , PZT, PLZT (PbTiO ₃ -PbZrO ₃ Oxides), oxides of multiple oxides such as ferrite; Si ₃ N ₄ , Si _6-Z Al _Z O _Z N _8-Z , AlN, BN, TiN and other nitride-based non-oxides; SiC, B ₄ Carbide-based non-oxide such as C, TiC, WC; LaB ₆ , TiB ₂ , ZrB ₂ Boride-based non-oxides such as CdS, MoS ₂ Sulfide-based non-oxide such as MoSi ₂ And the like. Non-oxides of silicide series such as, for example; non-oxides of carbon series such as amorphous carbon, graphite, and diamond;
[0019]
When the light absorbing function is imparted to the deformable layer, the deformable layer has a relatively large absorption coefficient with respect to the recording wavelength (the absorption coefficient is an imaginary part of the complex refractive index, for example, preferably 0.2 or more). There is no limitation as long as it has a material. Examples thereof include materials containing Si or Ge (eg, Si, Ge, Si _x Ge _1-x , Mg ₂ Ge, Mg ₂ Si, SiC, etc.); metals such as Nb, Ta, Be, V, or metal oxides thereof (eg, Ta) ₂ O ₅ , Nb ₂ O ₅ Etc.); AlSb, Al _x Ga _1-x As, CdSe, GaSb, Hg _1-x Cd _x Semiconductors such as Te, Se, Te, ZnTe, ZnS, PbS, InP, and GaP; or metals such as Ni, Cr, Ti, Ta, and Fe having lower thermal conductivity than Ag and the like, and Cu / Al, Ni / An alloy such as Fe can be used.
[0020]
In the case where the interface between the deformed layer and the adjacent layer becomes the main reflection interface, the present invention compensates the deformed shape of the deformed layer (improves the symmetry of the deformed shape) in order to deform the deformed layer toward the incident light side. Of the deformation shape compensating layer is preferably an adjacent layer on the back side of the deformation layer when viewed from the incident light side.
Because, in the present invention, in order to compensate for the deformed shape of the deformed layer, the pressure based on the state change of the material constituting the deformed shape compensation layer, for example, expansion, decomposition, explosion, sublimation, etc. (If the deformed shape compensating layer is an adjacent layer on the near side of the deformed layer when viewed from the incident light side, the deformed layer is located on the side opposite to the incident light due to the pressure caused by the change in the state of the material constituting the deformed shape compensating layer. The recording polarity becomes low to high, the recording polarity changes depending on the recording mark length or recording power, or the reproduction signal waveform is differentiated).
Among the pressures based on the change in the state of the material constituting the deformed shape compensation layer, it is particularly preferable to use the pressure associated with decomposition, explosion, sublimation and the like.
[0021]
The deformed shape compensating layer must be made of a material that generates pressure toward the deformed layer as described above, and it is preferable to use an organic material. This is because the organic material causes decomposition, explosion, sublimation and the like in an appropriate recording power range.
Preferred organic materials include polymethine, naphthalocyanine, phthalocyanine, squarylium, croconium, pyrylium, naphthoquinone, anthraquinone (indanthrene), xanthene, triphenylmethane, azulene, and tetrahydrocholine. And phenanthrene-based and triphenothiazine-based dyes, and metal complex compounds.
The formation of the dye layer can be performed by ordinary means such as vapor deposition, sputtering, CVD, and solvent application. In the case of using a coating method, the above-mentioned coloring matter or the like may be dissolved in an organic solvent and applied by a conventional coating method such as spraying, roller coating, dipping, or spin coating.
[0022]
Examples of the organic solvent used include alcohols such as methanol, ethanol and isopropanol; ketones such as acetone, methyl ethyl ketone and cyclohexanone; amides such as N, N-dimethylacetamide and N, N-dimethylformamide; sulfoxides such as dimethylsulfoxide. Ethers such as tetrahydrofuran, dioxane, diethyl ether and ethylene glycol monomethyl ether; esters such as methyl acetate and ethyl acetate; aliphatic halogenated carbons such as chloroform, methylene chloride, dichloroethane, carbon tetrachloride, and trichloroethane; Aromatics such as benzene, xylene, monochlorobenzene and dichlorobenzene; cellosolves such as methoxyethanol and ethoxyethanol; hexane, pentane, Cyclohexane, and hydrocarbons such as methylcyclohexane.
The thickness of the dye layer (deformation compensation layer) is 10 nm to 10 μm, preferably 10 to 200 nm.
[0023]
In addition to the above, the deformed shape compensation layer may be made of a gas generating compound that decomposes by heat.
As a specific example of the gas generating compound, it is necessary to appropriately select a decomposition temperature, a decomposition rate, and the like. Examples of the organic compound include dinitrosopentamethylenetetramine (DPT), N, N'-dimethyl-N, Nitroso compounds such as N'-dinitrosoterephthalamide (DMDNTA); benzenesulfonylhydrazide (BSH), p-toluenesulfonylhydrazide (TSH), diphenylsulfone-S, S'-disulfonylhydrazide (DPSDSH), 4 Sulfonyl hydrazide compounds such as 4,4'-oxybisbenzenesulfonylhydrazide (OBSH); azodicarboxylic amide (ADCA), azobisisobutyronitrile (AIBN), diazoaminobenzene (DAB), barium-azodicarboxylate Azo and diazo compounds such as trihydra Bruno triazine, p- toluenesulfonyl semicarbazide, include 4,4'-oxybisbenzenesulfonyl semicarbazide etc., sodium bicarbonate as inorganic compounds, ammonium carbonate, ammonium bicarbonate, ammonium nitrite, include peroxides.
[0024]
Any of the above organic compounds and inorganic compounds can be used alone or in combination of two or more.
Among the above gas generating compounds, the organic compound decomposes rapidly when reaching a certain temperature because the decomposition behavior is an exothermic reaction, so the amount of generated gas tends to be constant. It is preferable because it is easy to perform.
In addition, some inorganic compounds generally have a large endothermic reaction and gradually decompose. In such a case, it is desirable to control gas generation and the like.
Further, an auxiliary may be appropriately added to the gas generating compound, particularly an organic compound, in order to adjust the decomposition temperature.
[0025]
Examples of the auxiliaries include zinc compounds such as zinc white, zinc caprylate, zinc nitrate, and zinc fatty acid soap; and lead carbonate, lead phthalate, lead phosphite, and lead stearate. Cadmium compounds such as cadmium caprylate, cadmium caproate, cadmium laurate, cadmium myristate, and cadmium fatty acid soap; urea, borax, ethanolamine and the like. On the other hand, auxiliary agents that suppress decomposition include organic acids such as maleic acid and fumaric acid; halogenated organic acids such as stearoyl chloride and phthaloyl chloride; organic anhydrides such as maleic anhydride and phthalic anhydride; hydroquinone and naphthalene Polyhydric alcohols such as diols; hydrocarbons such as d-maltose; nitrogen-containing substances such as aliphatic amines, heterocyclic amines, amides and oximes; sulfur-containing substances such as thiols, mercaptans, sulfides, sulfonic acids, sulfoxides and isocyanates. Products: ketones such as cyclohexanone and acetylacetone; aldehydes; phosphates and phosphite compounds; 6,6-dimethylfulvene, hexachlorocyclopentadiene, dibutyltin maleate and the like are used. The decomposition behavior can be modified by using these auxiliaries as appropriate.
[0026]
In the present invention, the organic material layer is used as one constituent layer of the optical recording medium. However, since the pressure on the deformable layer based on the state change of the organic material is used, severe optical conditions as in the past are imposed on the organic material. Never.
Therefore, when increasing the reflectance at the time of non-recording, it is possible to use an organic material having a small absorption coefficient with respect to the recording / reproducing wavelength. By adjusting the absorption coefficient of the organic material layer according to the magnitude of the light absorption function of the deformable layer, recording can be performed with an appropriate recording power.
As described above, in the present invention, since it is basically unnecessary to use the change in the complex refractive index of the organic material, strict optical conditions are not imposed on the organic material, and a very large number of materials can be used as the organic material. It becomes.
As a result, in the conventional recording / reproducing method in which the absorption band is positioned on the short wavelength side with respect to the recording / reproducing wavelength, for example, when the recording / reproducing wavelength is 450 nm or less, a conjugate system of an organic material or the like is basically used. Due to the need to reduce the molecular skeleton, the stability of the organic material deteriorates (crystallization or aggregation occurs over time), the solubility deteriorates, and the wavelength control deteriorates (reduction of the number of substituents introduced, and However, these problems do not occur in the present invention.
That is, the physical properties of the organic material can be changed very widely and flexibly according to the purpose, and the recording / reproducing characteristics can be improved.
[0027]
For example, in the write-once optical recording medium of the present invention, a dye used for, for example, a CD-R or a DVD-R can be used, even though the optical recording medium is compatible with a blue wavelength or less. An optical recording medium that can be reproduced can be provided.
In the present invention, basically, it is not necessary to use the change in the optical constant (complex refractive index) of the organic material for recording / reproduction, but it is needless to say that the change in the optical constant of the organic material may be used.
As described above, in order to compensate for the deformed shape of the deformed layer, explosion, decomposition, and sublimation of the material constituting the deformed shape compensating layer have been described. A preferred example of the material is described above. When the expansion pressure of the material to be used is used, for example, a polymer material can be used.
Examples of such a polymer material include polynorbornene, polyisoprene, styrene / butadiene copolymer, polyurethane, polyolefin resin, fluorinated resin, polycaprolactone resin, polyamide resin and the like. Further, a polymer material that can be used as a deformation receiving layer, which will be described later, can also be used. Further, these polymer materials can be used in combination with a dye.
[0028]
In the present invention, a deformation receiving layer is further provided as an adjacent layer on the side opposite to the deformation shape compensation layer among the adjacent layers of the deformation layer.
This deformation receiving layer is provided to reduce the variation in the amount of deformation of the deformation layer with respect to the change in recording power, and is very effective in expanding the recording power margin. Therefore, it is preferable that the deformation receiving layer is made of a material that hardly generates pressure on the deformation layer side due to a state change due to recording, contrary to the deformation shape compensation layer. That is, the deformation receiving layer should be made of a material that hardly causes large decomposition, explosion, sublimation, or the like by recording, or a material and a film thickness that does not increase the pressure on the deformation layer even when decomposition, explosion, sublimation, or the like occurs. Is preferred.
Therefore, it is preferable to use an inexpensive polymer compound for easy film formation as the deformation receiving layer.
Examples of the polymer compound include an acrylic resin, a polycarbonate resin, a polyester resin, a polyamide resin, a vinyl chloride resin, a polyvinyl ester resin, a polystyrene resin, a polyolefin resin, and a polyether sulfone resin.
[0029]
Specific examples include polystyrene, poly (α-methylstyrene), polyindene, poly (4-methyl-1-pentene), polyvinylpyridine, polyvinylformal, polyvinylacetal, polyvinylbutyral, polyvinyl acetate, polyvinyl alcohol, and polyvinyl chloride. , Polyvinylidene chloride, polyvinyl methyl ether, polyvinyl ethyl ether, polyvinyl benzyl ether, polyvinyl methyl ketone, poly (N-vinyl carbazole), poly (N-vinyl pyrrolidone), poly (methyl acrylate), poly (ethyl acrylate), poly (acrylic acid) , Polyacrylonitrile, polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polybenzyl methacrylate, polycyclohexyl methacrylate, polymethacrylic acid, poly Tacrylamide, polymethacrylonitrile, polyacetaldehyde, polychloral, polyethylene oxide, polypropylene oxide, polyethylene terephthalate, polybutylene terephthalate, polycarbonates (bisphenols + carbonic acid), poly (diethylene glycol bisallyl carbonate), 6-nylon 6,6-nylon, 12-nylon, 6,12-nylon, ethyl polyaspartate, ethyl polyglutamate, polylysine, polyproline, poly (γ-benzyl-L-glutamate), methylcellulose, ethylcellulose, benzylcellulose, hydroxy Ethyl cellulose, hydroxypropyl cellulose, acetyl cellulose, cellulose triacetate, cellulose tributyrate, polyurethane Resins such as fats; the like, or a copolymer or co-polycondensate thereof; organic polygermane; poly (phenyl methyl silane) organic polysilane such.
[0030]
Further, it is also possible to use a dye having characteristics that do not cause large decomposition, explosion, sublimation, etc. as the deformation receiving layer. In this case, it is preferable that the decomposition temperature of the dye is sufficiently lower or sufficiently higher than the deformation temperature of the deformation layer.
Although the thickness of the deformation receiving layer is arbitrary, when a material having high hardness is provided adjacent to the deformation receiving layer, it is preferable to determine the film thickness in consideration of the recording sensitivity and the recording power margin.
The deformation receiving layer referred to in the present invention can be any layer as long as the deformation receiving layer is not formed of a material that completely inhibits deformation of the deformed layer or a material that deteriorates the symmetry of the deformed shape. For example, it may be an air layer, an adhesive layer, a protective layer, a cover layer, or the like.
[0031]
In the present invention, information is recorded / reproduced by deformation of the deformed layer, and the deformation of the deformed layer is performed such that the deformed layer has a light absorbing function alone or the deformed shape compensation layer has a light absorbing function alone. Alternatively, it can be achieved by providing both the deformed layer and the deformed shape compensation layer with a light absorbing function.
However, in order to enhance the reproduction stability and storage stability after recording, it is preferable that the light absorption function is reduced in the recording section.
Therefore, in the present invention, it is particularly preferable that both the deformed layer and the deformed shape compensating layer have a light absorbing function, and the light absorbing function of the deformed shape compensating layer is reduced or eliminated by recording.
Because, in the present invention, the deformable layer is preferably composed of a material that does not cause decomposition or sublimation by recording, and it is generally difficult to reduce or eliminate the light absorption function of the deformable layer by recording. On the other hand, the deformed shape compensation layer is preferably formed of a material that easily undergoes decomposition, sublimation, or the like by recording, and it is easy to reduce or eliminate the light absorption function of the deformed shape compensation layer by recording.
As a result, the light absorption function of the recording section after recording can be reduced, deterioration due to reproduction can be prevented, and stability is improved.
[0032]
The present invention can provide a "write-once type optical recording medium having a simple layer structure and inexpensive manufacture and a method for recording and reproducing the same", because the simplest recording principle of deformation is used.
In addition, the reason that “the write-once optical recording medium and the recording / reproducing method of the recording / reproducing wavelength are not largely limited and the recording characteristics are less dependent on the wavelength” can be provided, for example, by using a deformable layer having a light absorbing function for recording light. In this case, Si or Ge-containing materials such as SiC, Si, and Ge are preferably used as the deformable layer, and the complex refractive index of these materials has a large wavelength such as an organic material used in a conventional write-once optical recording medium. This is because there is no dependency.
In addition, the reason that the “write-once optical recording medium capable of supporting surface recording or recording with a high NA lens and achieving a high density and a recording / reproducing method thereof” can be provided is because of the configuration and the recording principle of the optical recording medium of the present invention. This is because there is no limitation on the recording / reproducing direction (in any case, the recording / reproducing direction can easily realize a layer configuration corresponding to the direction). Further, in the present invention, the deformation direction of the deformation layer with respect to the incident light is defined. However, as described above, this is to make the polarity of the reproduction signal High to Low and to prevent the waveform from being differentiated. In the case where no problem such as the recording polarity or the differential waveform occurs or the problem does not occur, the relationship between the deformation direction of the deformable layer and the incident light may be arbitrary.
[0033]
In the present invention, a reflective layer may be provided.
As the material of the reflection layer, a substance having a high reflectance to laser light is suitable. For example, Mg, Se, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Metals such as Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Si, Ge, Te, Pb, Po, Sn, Bi, etc. Metal or stainless steel can be used.
Preferred among these are Cr, Ni, Pt, Cu, Ag, Au, Al and stainless steel.
These substances may be used alone, in combination of two or more, or as an alloy.
The reflection layer can be formed by, for example, vapor deposition, sputtering, or ion plating of the above substance.
The thickness of the reflective layer is usually 10 to 500 nm, preferably in the range of 10 to 300 nm.
[0034]
Embodiments of the present invention are as shown in FIGS.
FIG. 3 shows an example having a structure in which the deformed shape compensation layer and the deformation receiving layer of the present invention are adjacent to the deformed layer (the essential layer structure of the present invention).
FIG. 4 is a diagram showing a deformation direction and a reproduction direction of the deformable layer when the main reflection interface has the structure of FIG. 3 and is located at the interface between the deformable layer and the deformation receiving layer. In FIG. 4, the deformable layer is deformed toward the deformation receiving layer by the light absorption function of the deformable layer and / or the deformable shape compensation layer. FIG. 5 is a diagram illustrating an example in which the layer configuration having the structure and function of FIG. 4 is applied to an actual write-once optical recording medium, that is, an example in which the layer configuration of FIG. 4 is stacked on a substrate.
FIG. 6 shows another example in which the layer configuration having the structure and function of FIG. 4 is applied to an actual write-once optical recording medium, that is, the layer configuration of FIG. It is a figure showing the example which provided the cover layer.
FIG. 7 shows still another example in which the layer configuration having the structure and function of FIG. 4 is applied to an actual write-once optical recording medium, that is, the layer configuration of FIG. FIG. 3 is a diagram showing an example in which a cover layer is provided via an adhesive layer.
[0035]
FIG. 8 shows a structure having the structure of FIG. 3 and having a reflective layer as an adjacent layer on the side opposite to the deformation layer of the deformation receiving layer, wherein the main reflection interface is at the interface between the deformation reception layer and the reflection layer. FIG. 5 is a diagram showing a deformation direction and a reproduction direction of a deformation layer of FIG.
In FIG. 8, the deformation layer is deformed toward the deformation receiving layer by the light absorption function of the deformation layer and / or the deformation shape compensation layer.
FIG. 9 is a diagram showing an example in which the layer configuration having the structure and function of FIG. 8 is applied to an actual write-once optical recording medium, that is, an example in which the layer configuration of FIG. 8 is laminated on a substrate.
Note that “A” in FIGS. 3 to 9 indicates a portion where the deformed layer and the deformed shape compensation layer are separated, a portion where the deformed shape compensation layer is expanded, or a portion where the deformed layer is expanded.
In addition, in FIGS. 3 to 9, the deformed shape compensation layer in the portion where the deformation of the deformed layer has occurred may have a change in the optical constant.
FIG. 3 to FIG. 9 described above show examples having the minimum number of layers exhibiting the effects of the present invention. In fact, in addition to the layer configurations shown in FIG. 3 to FIG. A substrate, an undercoat layer, an overcoat layer, a protective layer, an adhesive layer, a cover layer and the like are provided.
[0036]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, Comparative Examples, and Reference Examples, but the present invention is not limited to these Examples.
[0037]
Comparative Example 1
On a polycarbonate substrate having a guide groove with a groove depth of 55 nm, a dye layer composed of the following [Chemical Formula 1], which can be used for DVD-R as a deformation shape compensation layer, having a thickness of about 60 nm and further having a light absorbing function thereon An optical recording medium provided with SiC as a layer having a thickness of 10 nm was manufactured.
The optical recording medium was irradiated with a 9.0 mW laser beam from the SiC side using an optical disk evaluation device DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial. A signal of 8-16 modulation was recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s (at a groove position on the near side when viewed from the incident laser beam side).
As a result, the modulation degree was about 70%, the recording polarity was High to Low, a very clear eye pattern as shown in FIG. 19 was obtained, and the jitter (σ / Tw) was 7.8%. became.
In addition, the jitter characteristic with respect to the recording power was as indicated by the line indicated by ◆ in FIG. 20, and it was confirmed that the jitter value was better and the recording power margin was wider than in Comparative Example 2 described later.
FIG. 20 also shows the measurement results (line indicated by Δ) when the thickness of the dye layer was 50 nm in this comparative example.
At this time, the deformation state of the deformed layer was confirmed by an AFM (atomic force microscope). As shown in FIG. 22, the deformed layer was deformed toward the incident light side, and the deformed shape had good symmetry. there were.
[0038]
Embedded image

[0039]
Example 1
On a polycarbonate substrate having a guide groove with a groove depth of 55 nm, a dye layer composed of the dye of the above formula [1], which can be used for DVD-R as a deformed shape compensation layer, has a thickness of about 60 nm and has a light absorbing function thereon. An optical recording medium having a thickness of 10 nm of SiC as a deformation layer and a thickness of about 2 μm of a polystyrene resin as a deformation receiving layer thereon was prepared.
The optical recording medium was irradiated with 9.7 mW laser light from the polystyrene resin layer side using an optical disk evaluation device manufactured by Pulstec Industrial, DDU-1000 (wavelength: 405 nm, NA: 0.65). An 8-16 modulation signal was recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s on the land (groove position on the near side when viewed from the incident laser beam side).
As a result, the degree of modulation was about 61%, the recording polarity was High to Low, a clear eye pattern was obtained as in Comparative Example 1, and the jitter (σ / Tw) was 8.0%.
Further, the jitter characteristic with respect to the recording power is as shown by the line indicated by ■ in FIG. 24, and it can be confirmed that the recording power margin is wider than that of the disk of Comparative Example 1 (the line indicated by ◆ in FIG. 24). (The effect of the deformation receiving layer was confirmed.)
At this time, the polystyrene resin layer was peeled off, and the deformation state of the deformation layer was confirmed by AFM. As shown in FIG. 23, the deformation layer was deformed toward the incident light side (polystyrene resin layer side). Had good symmetry. Note that the white dotted line in FIG. 23 is a line indicating the mark center.
[0040]
Comparative Example 2
An optical recording medium having a thickness of 10 nm as SiC as a deformable layer having a light absorbing function was manufactured on a polycarbonate substrate having a guide groove with a groove depth of 55 nm.
The optical recording medium was irradiated with 8.0 mW of laser light from the SiC side using an optical disk evaluation device DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial. A signal of 8-16 modulation was recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s (at a groove position on the near side when viewed from the incident laser beam side).
As a result, the modulation degree was about 70%, the recording polarity was High to Low, and a relatively good eye pattern as shown in FIG. 18 was obtained, but the jitter (σ / Tw) was 10.4%. And became bigger.
Further, the jitter characteristic with respect to the recording power was as indicated by the line indicated by ● in FIG. 20, and it was confirmed that the jitter value was lower and the recording power margin was narrower than in Comparative Example 1 described above.
At this time, the deformation state of the deformed layer was confirmed by AFM. As shown in FIG. 21, the deformed layer was deformed toward the incident light side, but the symmetry of the deformed shape was largely lost. Note that the white dotted line in FIG. 21 is a line indicating the mark center.
As described above, the results of Comparative Example 1 and Comparative Example 2 show the effectiveness of the deformed shape compensation layer, and the results of Comparative Example 1 and Example 1 show the effectiveness of the deformation receiving layer.
[0041]
Example 2
On a polycarbonate substrate having a guide groove having a groove depth of 55 nm, a dye layer made of the following formula (2) having an absorption at a blue laser wavelength as a deformed shape compensating layer having a thickness of about 20 nm and being formed of SiC as a deformed layer having a light absorbing function. An optical recording medium having a thickness of about 5 nm, a layer made of a polystyrene resin as a deformation receiving layer having a thickness of about 80 nm, and a reflecting layer having a thickness of about 100 nm of Ag was prepared.
The optical recording medium is irradiated with 9.5 mW laser light from the substrate side using a DDU-1000 (wavelength: 405 nm, NA: 0.65) optical disc evaluation device manufactured by Pulstec Industrial. A signal of 8-16 modulation was recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s (at a groove position on the back side when viewed from the incident laser beam side).
As a result, the jitter characteristic with respect to the recording power was as indicated by the line indicated by the triangle in FIG. 25, and it was confirmed that the jitter value was better than that of Comparative Example 3 described later.
Further, there was almost no reproduction deterioration due to repeated reproduction, and it was confirmed that the dye layer in the recording portion was decomposed and deteriorated.
[0042]
Embedded image

[0043]
Comparative Example 3
On a polycarbonate substrate having a guide groove with a groove depth of 55 nm, a thickness of about 10 nm of SiC as a deformation layer having a light absorption function, a thickness of about 80 nm of a layer made of a polystyrene resin as a deformation receiving layer, and a thickness of Ag as a reflection layer. An optical recording medium having a thickness of about 100 nm was manufactured.
The optical recording medium was irradiated with 9.8 mW laser light from the substrate side using a DDU-1000 (wavelength: 405 nm, NA: 0.65) optical disk evaluation device manufactured by Pulstec Industrial. A signal of 8-16 modulation was recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s in the portion (groove position on the back side when viewed from the incident laser beam side).
As a result, the jitter characteristic with respect to the recording power was as indicated by the line indicated by the triangle in FIG. 25, and the value of the jitter was worse than that in the above-described Example 2.
[0044]
As described above, in the examples, the effects of the deformable shape compensation layer and the deformation receiving layer of the present invention were confirmed. However, in the present invention, by providing the light absorbing layer with a light absorbing function necessary for recording, Since it was not necessary to provide the shape compensation layer with a large light absorbing function, it was confirmed that the thickness of the dye layer could be reduced, and that a shallow groove substrate could be used.
Further, in each of the above embodiments, recording was performed on the land portion, but this is for making it easier to observe the deformed shape of the deformed layer, and the present invention is not limited to land recording.
[0045]
Next, Reference Examples 1 to 8 show the importance of deforming the deformable layer to the incident light side when the interface between the deformable layer and the adjacent layer becomes the main reflection interface. In these reference examples, In order to clarify the effect of deformation of the deformable layer, an experiment was performed on an optical recording medium without a deformable shape compensation layer (the same phenomenon as in these reference examples was obtained when a deformable shape compensation layer was provided).
FIGS. 10 to 17 are diagrams showing recording results of Reference Examples 1 to 8, respectively. FIGS. 10A to 17A are diagrams showing the results of measuring the recording mark length (Mark Length) dependence of the reproduction signals (RF levels) of Reference Examples 1 to 8, and FIG. Unrec is the reproduction signal (RF level) at the time of non-recording, Top is the maximum reproduction signal level (that is, the space part) at the time of recording the mark sequence, Bottom is the minimum reproduction signal level at the time of recording the mark sequence, and MA is Indicates a modulation degree calculated by (Top-Bottom) / Top.
FIGS. 10 (b) to 16 (b) show a reproduced signal when a 3T mark is continuously recorded, a reproduced signal when a 4T mark is continuously recorded, and a reproduced signal when not recorded. The levels are shown in FIGS. 10 (c) to 16 (c) as a reproduction signal when a 6T mark is continuously recorded, a reproduction signal when an 8T mark is continuously recorded, and a reproduction when not recorded. The signal levels are shown in FIGS. 10 (d) to 17 (d) as a reproduction signal when a 3T mark is continuously recorded, a reproduction signal when a 14T mark is continuously recorded, and a reproduction signal when no recording is performed. The reproduction signal level is shown.
[0046]
Reference Example 1
An optical recording medium having a thickness of 10 nm as SiC as a deformable layer having a light absorbing function was manufactured on a polycarbonate substrate having a guide groove with a groove depth of 55 nm.
The optical recording medium was irradiated with a 5.0 mW laser beam from the substrate side using a DUT-1000 (wavelength: 405 nm, NA: 0.65) optical disk evaluation device manufactured by Pulstec Industrial to produce a groove portion. At a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s, 3T to 14T marks were recorded independently (at the groove position on the near side when viewed from the incident laser beam side).
It was confirmed by AFM that SiC was deformed on the side opposite to the incident light (opposite the substrate).
Also, from the result of FIG. 10A, it can be confirmed that High to Low recording may be performed regardless of the recording mark length.
Further, from the results of FIGS. 10B to 10D, it can be seen that all of the 3T, 4T, 6T, 8T, and 14T show reproduction signal waveforms that allow mark length recording.
[0047]
Reference Example 2
The same experiment as in Reference Example 1 was performed except that the recording power was set to 6.0 mW. It was confirmed by AFM that SiC was deformed on the side opposite to the incident light (opposite the substrate).
Also, from the results of FIG. 11A, the recording polarity changes depending on the recording mark length, that is, high-to-low recording is performed for a short mark, but high-to-low recording and low-to-high recording are mixed for a long mark. It can be seen that such a signal is generated and it becomes difficult to record the mark length.
Further, from the results of FIG. 11B to FIG. 11D, 3T and 4T show the reproduced signal waveforms that can be recorded with the mark length, but the 6T, 8T, and 14T greatly increase the RF level at the center of the mark. 5 shows a reproduction signal waveform [at 6T and 8T, the period of the reproduction signal looks twice as long as the original reproduction signal. This can be clearly understood in comparison with FIG. 10 (c)]. It can be seen that mark length recording becomes difficult.
[0048]
Reference Example 3
An experiment was performed in exactly the same manner as in Reference Example 1, except that a laser beam of 6.0 mW was irradiated from the substrate side and recording was performed on the land (groove position on the back side as viewed from the incident laser beam side). It was confirmed by AFM that SiC was deformed on the side opposite to the incident light (opposite the substrate).
Also, from the result of FIG. 12A, the recording polarity tends to change depending on the recording mark length, that is, high-to-low recording is performed for a short mark, but high-to-low recording and low-to-high recording are mixed for a long mark. Such a signal tends to be generated, and it is understood that there is a possibility that the recording of the mark length becomes difficult. Further, from the results of FIG. 12B to FIG. 12D, 3T, 4T, 6T, and 8T show the reproduction signal waveforms capable of recording the mark length, while 14T shows that the RF level at the center of the mark greatly increases. This shows that the reproduced signal waveform becomes difficult to record the mark length.
[0049]
Reference example 4
An experiment was performed in exactly the same manner as in Reference Example 1, except that 7.0 mW of laser light was irradiated from the substrate side and recording was performed on the land (groove position on the back side as viewed from the incident laser light side). It was confirmed by AFM that SiC was deformed on the side opposite to the incident light (opposite the substrate).
Further, from the result of FIG. 13A, the recording polarity changes depending on the recording mark length, that is, high-to-low recording is performed for a short mark, but high-to-low recording and low-to-high recording are mixed for a long mark. It can be seen that such a signal is generated and it becomes difficult to record the mark length.
Further, from the results of FIG. 13B to FIG. 13D, 3T and 4T show reproduction signal waveforms that can be recorded with a mark length, but 6T, 8T, and 14T show a large increase in the RF level at the center of the mark. [For example, at 6T, the period of the reproduced signal looks twice as long as the original reproduced signal. This can be clearly understood in comparison with FIG. 10 (c)]. It can be seen that mark length recording becomes difficult.
[0050]
As described above, from the results of Reference Examples 1 to 4, the interface between the deformed layer and the adjacent layer becomes the main reflection interface, and the deformed layer has a simple layer structure in which the deformed layer having the light absorbing function is provided on the substrate. In the case where the recording medium is deformed to the opposite side (in this case, in the method of recording / reproducing from the substrate side), it is often difficult to perform recording / reproduction by the mark length, and the recording polarity is low.
It was confirmed that there were many cases where to-High was performed.
[0051]
Reference example 5
An optical recording medium having a thickness of 10 nm as SiC as a deformable layer having a light absorbing function was manufactured on a polycarbonate substrate having a guide groove with a groove depth of 55 nm.
The optical recording medium was irradiated with 8.0 mW of laser light from the SiC side using an optical disk evaluation device DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial. At a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s, 3T to 14T marks were recorded independently (at the groove position on the near side when viewed from the incident laser beam side).
It was confirmed by AFM that SiC was deformed toward the incident light side (opposite the substrate side).
Also, from the results of FIG. 14A, it can be confirmed that High to Low recording may be performed regardless of the recording mark length.
Further, from the results of FIGS. 14B to 14D, it can be seen that all of the 3T, 4T, 6T, 8T, and 14T show the reproduction signal waveforms that can record the mark length.
[0052]
Reference Example 6
The same experiment as in Reference Example 5 was performed except that the recording power was set to 9.0 mW. It was confirmed by AFM that SiC was deformed toward the incident light side (opposite the substrate side).
Also, from the results of FIG. 15A, it can be confirmed that High to Low recording may be performed regardless of the recording mark length.
Further, from the results of FIG. 15B to FIG. 15D, it can be seen that the 3T, 4T, 6T, 8T, and 14T all show reproduction signal waveforms that allow mark length recording.
[0053]
Reference Example 7
The same experiment as in Reference Example 5 was conducted except that the laser beam of 7.0 mW was irradiated from the SiC side and recording was performed in the groove portion (groove position on the back side as viewed from the incident laser beam side). . It was confirmed by AFM that SiC was deformed toward the incident light side (opposite the substrate side).
Also, from the result of FIG. 16A, it can be confirmed that High to Low recording may be performed regardless of the recording mark length.
Further, from the results of FIGS. 16B to 16D, it can be seen that all of the 3T, 4T, 6T, 8T, and 14T show the reproduction signal waveforms capable of recording the mark length.
[0054]
Reference Example 8
An experiment was performed in exactly the same manner as in Reference Example 5, except that laser light of 8.0 mW was irradiated from the substrate side and recording was performed in the groove portion (groove position on the back side as viewed from the incident laser light side). It was confirmed by AFM that SiC was deformed toward the incident light side (opposite the substrate side).
Also, from the result of FIG. 17A, it can be confirmed that High to Low recording may be performed regardless of the recording mark length.
Further, from the result of FIG. 17D, it can be seen that both the shortest and longest marks show a reproduction signal waveform capable of recording the mark length.
[0055]
As described above, as shown in Reference Examples 5 to 8, the interface between the deformable layer and the adjacent layer is a main reflection interface, and is a simple optical recording medium in which only a deformable layer having a light absorbing function is provided on a substrate. When the deformable layer is deformed to the incident light side (in this case, the method of recording and reproducing from the opposite side of the substrate), it is proved by an experiment that the mark length can be recorded and the High to Low recording can be performed. Was done.
[0056]
【The invention's effect】
According to the present inventions 1 to 22, it can be manufactured at a low cost with a simple layer configuration, there is no great limitation on the recording / reproducing wavelength, the wavelength dependence of recording characteristics is small, and even when an organic material is used, Strict optical conditions are not required, and good jitter and a wide recording power margin can be achieved despite using the recording principle mainly based on deformation, and it can be used for surface recording or recording with a high NA lens. It is possible to provide a write-once optical recording medium having a characteristic that a high density can be achieved, and a recording / reproducing method thereof.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating the symmetry of a deformed shape of a deformable layer.
(A) An example of a deformed shape with reduced symmetry.
(B) An example of an ideal deformed shape.
FIG. 2 is a view for explaining a waveform of a reproduction signal when a recording mark of mark length recording is reproduced.
(A) General case
(B) Differential waveform with inflection points near the leading and trailing edges of the recording mark
(C) Differential waveform with inflection point near the center of the recording mark
FIG. 3 is a diagram showing an example having a structure in which a deformation shape compensating layer and a deformation receiving layer are adjacent to a deformation layer.
FIG. 4 is a view showing a deformation direction and a reproduction direction of the deformation layer when the main reflection interface is located at the interface between the deformation layer and the deformation receiving layer, having the structure of FIG. 3;
5 is a diagram showing an example in which the layer configuration having the structure and function of FIG. 4 is applied to an actual write-once optical recording medium, that is, an example in which the layer configuration of FIG. 4 is laminated on a substrate.
6 is another example in which the layer configuration having the structure and function of FIG. 4 is applied to an actual write-once optical recording medium, that is, the layer configuration of FIG. 4 is laminated on a substrate, and further formed on a deformation receiving layer. The figure which shows the example in which the cover layer was provided.
FIG. 7 shows still another example in which the layer configuration having the structure and function of FIG. 4 is applied to an actual write-once optical recording medium, that is, the layer configuration of FIG. The figure which shows the example which provided the cover layer via the adhesive layer in FIG.
8 is a structure having the structure of FIG. 3 and having a reflective layer as an adjacent layer on the side opposite to the deformation layer of the deformation receiving layer, wherein the main reflection interface is at the interface between the deformation reception layer and the reflection layer; FIG. 4 is a diagram showing a deformation direction and a reproduction direction of a deformable layer.
9 is a diagram showing an example in which the layer configuration having the structure and function of FIG. 8 is applied to an actual write-once optical recording medium, that is, an example in which the layer configuration of FIG. 8 is stacked on a substrate.
FIG. 10 is a diagram showing a recording result of Reference Example 1.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 11 is a diagram showing a recording result of Reference Example 2.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 12 is a view showing a recording result of Reference Example 3;
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 13 is a view showing a recording result of Reference Example 4.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 14 is a view showing a recording result of Reference Example 5.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) a reproduced signal when 3T marks and 14T marks are continuously recorded, and
This shows the reproduction signal level at the time of unrecording.
FIG. 15 is a view showing a recording result of Reference Example 6.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 16 is a view showing a recording result of Reference Example 7;
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(B) The reproduction signal level when the 3T mark and the 4T mark are continuously recorded, and the reproduction signal level when not recorded.
(C) The reproduction signal level when the 6T mark and the 8T mark are continuously recorded and the reproduction signal level when the recording is not performed are shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 17 is a view showing a recording result of Reference Example 8.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the degree of modulation is shown.
(D) A reproduction signal level when a 3T mark and a 14T mark are continuously recorded, and a reproduction signal level when no recording is performed.
FIG. 18 is a diagram showing an eye pattern of the optical recording medium of Comparative Example 2.
FIG. 19 is a diagram showing an eye pattern of the optical recording medium of Comparative Example 1.
FIG. 20 is a view showing jitter characteristics with respect to recording power of each optical recording medium of Comparative Example 1 and Comparative Example 2.
FIG. 21 is a diagram illustrating a deformation state of a deformation layer of an optical recording medium of Comparative Example 2 measured by AFM.
FIG. 22 is a view showing a result of measuring a deformed state of a deformed layer of the optical recording medium of Comparative Example 1 by AFM.
FIG. 23 is a diagram showing the result of peeling off the polystyrene layer of the optical recording medium of Example 1 and measuring the deformation state of the deformation layer by AFM.
FIG. 24 is a view showing jitter characteristics with respect to the recording power of each optical recording medium of Comparative Example 1 and Example 1.
FIG. 25 is a diagram showing jitter characteristics with respect to recording power of each optical recording medium of Example 2 and Comparative Example 3.
FIG. 26 is a diagram showing a layer configuration of a conventional disk.
[Description of Symbols] A A portion where the deformed layer and the deformed shape compensation layer are separated, a portion where the deformed shape compensation layer is expanded, or a portion where the deformed layer is expanded.
Mark Length Mark length
T reference clock
RF Level (V) RF (reproduction signal) level (volt)
Modulated amplitude modulation degree
Unrec Reproduction signal (RF) level when not recording
Top Reproduced signal level when recording a mark sequence (that is, space part)
Bottom Minimum reproduction signal level when a mark sequence is recorded (that is, mark portion)
Modulation degree calculated by MA (Top-Bottom) / Top
Time 0.5 (μs / div) Time (1 memory 0.5 microsecond)
σ / Tw jitter

Claims (22)

A write-once type optical recording characterized in that a deformation layer that causes deformation by recording has a structure sandwiched between a deformation shape compensation layer that compensates for the deformation shape of the deformation layer and a deformation receiving layer that receives deformation of the deformation layer. Medium. 2. The write-once optical recording medium according to claim 1, wherein the interface between the deformation layer and the deformation receiving layer is a main reflection interface, and the reproduction is performed from the deformation receiving layer side. 3. The write-once optical recording medium according to claim 2, wherein the recording portion is formed by deformation of the deformation layer toward the deformation receiving layer. It has a structure in which a deformation shape compensation layer for compensating for the deformation shape of the deformation layer, a deformation layer for causing deformation by recording, a deformation reception layer for receiving deformation of the deformation layer, and a reflection layer are sequentially provided. 2. The write-once optical recording medium according to claim 1, wherein an interface of the layer is a main reflection interface, and reproduction is performed from a deformation shape compensation layer side. 5. The write-once optical recording medium according to claim 4, wherein the recording portion is formed by deformation of the deformation layer toward the deformation receiving layer. 6. The write-once optical recording medium according to claim 1, wherein a deformed portion is formed in the deformable layer by a light absorbing function of the deformable layer. 6. The write-once optical recording medium according to claim 1, wherein a deformed portion is formed in the deformable layer by a light absorbing function of the deformable shape compensation layer. The deformed layer and the deformed shape compensating layer have a light absorbing function for recording light, and a deformed portion is formed in the deformed layer by the light absorbing function of the two, and the light absorbing function of the deformed shape compensating layer is reduced or eliminated by recording. The write-once optical recording medium according to claim 1, wherein: 9. The write-once optical recording medium according to claim 1, wherein the deformable shape compensation layer is made of an organic material. The write-once optical recording medium according to claim 9, wherein the organic material is a dye. The write-once optical recording medium according to claim 1, wherein the deformation receiving layer is made of a polymer compound. The write-once optical recording medium according to claim 1, wherein the deformation layer contains Si or Ge. 13. The write-once optical recording medium according to claim 12, wherein recording / reproduction is possible in a laser wavelength range of 350 to 500 nm. A recording method for a write-once optical recording medium having a structure in which a deformable layer deformed by recording is sandwiched between a deformable shape compensating layer for compensating for the deformed shape of the deformed layer and a deformation receiving layer for receiving deformation of the deformed layer. Wherein the deformable layer is deformed toward the deformation receiving layer by recording. A deformation layer that causes deformation by recording has a structure sandwiched between a deformation shape compensation layer that compensates the deformation shape of the deformation layer and a deformation reception layer that receives deformation of the deformation layer, and the deformation layer and the deformation reception layer A method of recording on a write-once optical recording medium, in which reproduction is performed from the deformation receiving layer side, wherein the interface is a main reflection interface, wherein the deformation layer is deformed to the deformation receiving layer side by recording. Recording method of recording medium. It has a structure in which a deformation shape compensation layer for compensating for the deformation shape of the deformation layer, a deformation layer for causing deformation by recording, a deformation reception layer for receiving deformation of the deformation layer, and a reflection layer are sequentially provided. A recording method for a write-once optical recording medium, wherein the interface of the layer is a main reflection interface and reproduction is performed from the deformation shape compensation layer side, wherein the recording deforms the deformation layer to the deformation receiving layer side. Recording method for optical recording media. The postscript according to any one of claims 14 to 16, wherein the deformation of the deformation layer toward the deformation receiving layer is caused by an expansion force of the deformation layer and / or a pressure accompanying a state change of the deformation shape compensation layer. Recording method for optical recording media. The deformation shape compensating layer is made of an organic material, and the deformation of the deformation layer toward the deformation receiving layer is caused by the expansion force of the deformation layer and / or the pressure accompanying the decomposition, explosion, or sublimation of the organic material forming the deformation shape compensating layer. 18. The recording method for a write-once optical recording medium according to claim 17, wherein the recording is performed by: 19. The recording method for a write-once optical recording medium according to claim 18, wherein the organic material is a dye. The deformation of the deformation layer toward the deformation receiving layer is caused by a light absorption function of the deformation layer by irradiation of recording light and / or a light absorption function of the deformation shape compensation layer. 3. The recording method for a write-once optical recording medium according to item 1. The deformation of the deformation layer toward the deformation receiving layer is caused by the light absorption function of the deformation layer by the irradiation of the recording light and the light absorption function of the deformation shape compensation layer, and the light absorption of the deformation shape compensation layer after the irradiation of the recording light. The recording method for a write-once optical recording medium according to claim 14, wherein the function is reduced or eliminated. 22. Recording on a write-once optical recording medium according to claim 14, wherein the deformable layer is made of a material containing Si or Ge, and performs recording / reproduction with a laser beam having a wavelength of 350 to 500 nm. Method.

Images